The present invention relates to data communications, and more particularly, to methods and apparatus for connecting a plurality of devices to a data communications network through a switching system.
Asynchronous Transfer Mode (ATM) is becoming an important standard for communications around the world. One reason for this is that ATM is essentially the only established standards based technology that has been designed from the beginning to accommodate the simultaneous transmission of data, voice and video. ATM is essentially a connection-oriented, switched based technology that provides dedicated bandwidth for each connection, a higher aggregate bandwidth, well defined connection procedures, and flexible access speeds ranging from Megabit to Gigabit speeds.
An ATM network basically consists of several ATM switches that are interconnected by various communication links. A typical ATM switch includes a programmable switch matrix or switch fabric that supports the interconnectivity for both local devices and other remote ATM switches and devices. The flexibility of the switch fabric allows for virtual circuits to be established between nodes using switching protocols and commands. Depending upon the type of transfer, these virtual circuits provide point-to-point connections that can be unidirectional or bidirectional. In this manner, an ATM network is essentially woven using the switch fabric provided by the various ATM switches.
FIG. 1 is a block diagram depicting a typical ATM network 100 having an ATM switch 102 that provides network connectivity for several devices 104, for example, numbered 1 through N. Devices 104 can include computers, hosts, routers, gateways, peripherals, appliances, and other like devices that are configured to send and/or receive the type of information (e.g., data, voice, video) carried by ATM network 100.
As shown, devices 104 are each connected to a dedicated device interface port 106 (numbed 1 through N) within ATM switch 102. On the network side of ATM switch 102, there are several network interface ports 108 (also, numbered 1 through N). ATM switch 102 provides the switch fabric that selectively connects together (and later disconnects) specified device interface ports and/or network interface ports to help establish a virtual circuit though ATM network 100. For example, in FIG. 1, a virtual circuit is depicted by the solid and dashed lines connecting device (#2) 104 to remote device 110, through ATM switch 102 and network links 112. Network links 112 typically includes one or more communication media, such as, for example, terrestrial and/or satellite communication lines/services.
As further depicted in FIG. 1, ATM switch 102 is limited in the number of devices 104 that can be supported by the xe2x80x9cNxe2x80x9d number of device interface ports 106 and the size of the switch fabric (i.e., Nxc3x97N). For example, certain ATM switches provide a 16xc3x9716 switch fabric (i.e., where N=16) having sixteen device interface ports 106 and sixteen network interface ports 108. As such, these ATM switches are limited to supporting sixteen devices 104. Larger ATM switches are available, for example, 32xc3x9732 switch fabrics are provided by certain manufacturers. These 32xc3x9732 and even larger ATM switches, however, tend to be very complex and expensive.
As can be appreciated, the fixed size and high cost of an ATM switch, can be problematic for users that want to xe2x80x9cphase-inxe2x80x9d an ATM network and/or provide for future expansion of the ATM network, for example, by adding additional devices to the ATM switch. Indeed, users, such as small businesses, that have limited communication funds may be forced to forego the development of an ATM network until such time as they can justify the purchase of a larger ATM switch. Other users may be forced to purchase too large an ATM switch. In a worse case scenario, the large ATM switch that is purchased exceeds their current demands, but will eventually lack the capacity to support their future growth and additional demands. Thus, there is a need for methods and apparatus that provide a more flexible and cost-effective ATM switching capability.
The methods and apparatus of the present invention provide a more flexible and cost-effective switching capability by allowing device interface ports within a switch fabric to be dynamically assigned in a manner that allows several devices to selectively access a single device interface port.
Thus, for example, assume that a user has a current need to provide connectivity for twelve devices. Assume also that the user plans to expand that need to twentyeight devices in the future. In the past, such a user might decide to incrementally purchase two 16xc3x9716 switches, or initially purchase one larger 32xc3x9732 switch. Both of these choices tend to be rather expensive and wasteful. Given the present invention, however, such a user can purchase one 16xc3x9716 switch, for example, and economically add configurable connections that allow up to about forty-eight devices to access the network through the 16xc3x9716 switch.
With this example in mind, in accordance with certain aspects of the present invention, flexible network connectivity is provided to a plurality of devices through a network interface that can be dynamically configured and reconfigured as needed, without interrupting existing network connections, to meet the current communication needs of the user.
In accordance with other aspects of the present invention, the various methods and apparatus provided allow a data communication system to exceed the network connectivity capabilities of a conventional network switch.
In accordance with still other aspects of the present invention, the various methods and apparatus provided allow for incremental growth of a system to more cost-effectively meet the users communication needs.
In accordance with further aspects of the present invention, the various methods and apparatus provide a lower cost solution to connecting a plurality of devices to a network through a limited number of communication paths.
In accordance with still further aspects of the present invention, the various methods and apparatus provided tend to reduce the complexity of a network switch by significantly reducing the size of the switch fabric therein, for example.
In accordance with additional aspects of the present invention, the various methods and apparatus provide enhanced configuration capabilities that can be used to automatically test various switch and network configurations and connections.
By way of example, the above stated needs and others are met by an apparatus for selectively connecting a plurality of external devices to a network, in accordance with certain embodiments of the present invention. The apparatus includes a selector and a switch. The selector has a plurality of input ports and a plurality of output ports. In certain preferred embodiments, the number of input ports within the selector is greater than the number of output ports within the selector, for example, certain selectors have at least about forty-eight input ports and at least about sixteen output ports.
While each of the input ports is configured to be connected to a different external device, the selector is dynamically configurable to selectively couple at least one of the input ports to at least one of the output ports. Thus, for example, at least one of the forty-eight input ports, or a subset thereof, can be selectively coupled to at least one of the sixteen output ports, or a subset thereof. This allows several devices to gain access to the network, without requiring a dedicated device interface port within the switch for each of the devices.
The switch has a plurality of device interface ports, for example xe2x80x9cNxe2x80x9d number, each of which is coupled to a corresponding output port in the selector. The switch is configured to switchably connect an individual device interface port to an identified network interface port, and thereby connect a particular device to the network through the identified network interface port.
In accordance with still other embodiments of the present invention, the selector is configured to be responsive to commands that are received through one of the input ports or output ports or through a separate control input. The commands cause the selector to be dynamically configured or reconfigured. For example, the selector can include a controller that is operatively configured to respond to the commands and dynamically reconfigure the selector such that a specified input port is connected or otherwise assigned to a specified output port. Additionally, the selector can also be configured to selectively couple at least one of the input ports to at least another one of the input ports, and/or at least one of the output ports to at least another one of the output ports. In this manner, enhanced loop-back types of diagnostic testing/evaluation, or even non-conventional connections or virtual circuits, can be realized.
In accordance with other embodiments of the present invention, a method is provided for connecting at least one external device to a network. The method includes the steps of connecting the external device to an input port of a selector, dynamically configuring the selector to selectively connect the input port to an output port within the selector, and connecting the output port to a device port in a switch. The method further includes the step of causing the switch to connect the device port to a network.